為什麽shower防水層（如hot mop）之前要做Pre Slope？網上的理由好像不make sense。真正理由是什麽？

網上的理由是“Without it, any moisture that works its way to the Hot Mop would have no where to go. Over time the moisture would build up bacteria and MOLD, that eventually come up through the grout joints.”但是moisture到了斜的Hot Mop還是和水平的Hot Mop一樣還是要停留那裏，隻是斜的Hot Mop會幫助moisture往低處（drain area）聚集。

寫了上麵一些時間後真正理由找到了，drain上有weep holes排水. 但是這個幫助有限，真正要做的是防止水到達防水層。